Traction Control Switch: Description and Operation
Anti-Lock Control - Traction Control - 4.2LCOMPONENT LOCATIONS - SHEET 1 OF 2
NOTE: LHD (left-hand drive) installation shown, RHD (right-hand drive) installation similar
COMPONENT LOCATIONS - SHEET 2 OF 2
NOTE: RHD (right-hand drive) installation shown, LHD (left-hand drive) installation similar
GENERAL
The anti-lock control - traction control system is based on the 4 channel Bosch 8.0 system and provides the following brake functions:
^ ARM (active roll mitigation).
^ ABS (anti-lock brake system).
^ CBC (corner brake control).
^ DSC.
^ EBD (electronic brake force distribution).
^ ETC (electronic traction control).
^ EBA (emergency brake assist).
^ EDC (engine drag-torque control).
^ HDC.
The system consists of the following components:
^ A DSC switch.
^ An HDC switch.
^ A stoplamp switch.
^ Four wheel speed sensors.
^ A yaw rate and lateral acceleration sensor.
^ A steering angle sensor.
^ Four warning indicators.
^ A HCU (hydraulic control unit) with attached ABS (anti-lock brake system) module.
DSC SWITCH
The DSC switch allows the DSC function to be selected off. Although Land Rover recommend that DSC is selected on for all normal driving conditions, it may be beneficial to de-select DSC, to maximize traction, under the following conditions:
^ If the vehicle needs to be rocked out of a hollow or a soft surface.
^ Driving on loose surfaces or with snow chains.
^ Driving in deep sand, snow or mud.
^ On tracks with deep longitudinal ruts.
The DSC switch is a non-latching switch installed in the center switch pack on the instrument panel. Pressing the DSC switch connects an ignition power feed to the ABS (anti-lock brake system) module. With the first press of the DSC switch, the ABS (anti-lock brake system) module disables the DSC functions. When the DSC switch is pressed again, the ABS (anti-lock brake system) module re-enables the DSC functions. The DSC switch must be pressed for a minimum of 0.3 s for the ABS (anti-lock brake system) module to react. The DSC function is re-enabled at the beginning of each ignition cycle.
The status of the DSC switch selection is shown by the DSC warning indicator. The DSC warning indicator is off while DSC is selected on, and continuously illuminated while DSC is selected off.
A DSC switch request to disable DSC is ignored by the ABS (anti-lock brake system) module if the air suspension system has failed, or is in off-road height at speeds above 60 km/h (37.5 mph).
To guard against incorrect operation or a broken switch, if the input from the DSC switch is held high for more than one minute, a failure is stored in the ABS (anti-lock brake system) module.
Even if DSC is deselected, driving maneuvers with extreme yaw or lateral acceleration may trigger DSC activity to assist vehicle stability.
HDC SWITCH
The HDC switch controls the selection of the HDC function.
The HDC switch is a non-latching switch installed on the center console, to the rear of the gear shift lever. Pressing and releasing the HDC switch momentarily connects an ignition power feed to the ABS (anti-lock brake system) module. With the first press and release of the HDC switch, the ABS (anti-lock brake system) module enables operation of the HDC function. When the HDC switch is pressed and released again, the ABS (anti-lock brake system) module disables operation of the HDC function.
To guard against incorrect operation or a broken switch, if the switch is pressed for more than 10 seconds no change of state occurs. If the input from the HDC switch is held high for more than one minute, a failure is stored in the ABS (antilock brake system) module.